The starting point would normally be to find an instructor to help you get going as learning to sit correctly is the fundamentals of riding sidesaddle safely and also elegantly. Within the UK, The Side Saddle Association (SSA) has a list of qualified SSA instructors. This is a very useful starting point.
At Simply Side Saddles, we regularly get people new to sidesaddle started on a “Have a Go” lesson/ clinic, where we provide the saddle to enable you to experience first hand what it’s like to ride side saddle. We have saddles available to fit most horses.
We also hold regular mechanical horse clinics sidesaddle which give you the opportunity to learn and perfect the skill, without having to worry about what the horse is doing.